1. Field of the Invention
This invention relates to solid-state photosensitive devices and more specifically to the read portion of such devices.
2. Description of the Prior Art
A photosensitive device of the type at present in use both in the visible region and in the infrared region of the electromagnetic wave spectrum has an array of N photosensors connected through a transition zone to a charge-coupled shift register having N parallel inputs and one series output. The shift register therefore receives at its input the charges detected by the photosensors and delivers these charges in series to a read stage which produces at its output an image-scan electric signal.
The use of a single charge-coupled shift register in the read portion of the photosensitive device is attended by a number of disadvantages.
When provision is made for a large number of photosensors or, in other words, when the shift register has a large number of stages, this in fact results in a large number of charge transfers into the shift register and in a high transfer rate in order to permit readout within a given period of time. This accordingly has an influence, not only on the power consumption and operating frequency of the entire circuit but also on the transfer noise and crosstalk produced by transfer ineffciecy into the shift register.
The object of the present invention is therefore to provide a remedy for these disadvantages by halving the number of charge transfers as well as the transfer rate.